The disclosure relates generally to turbomachine blade cooling, and more particularly, to a turbomachine blade having generally radial cooling conduit delivering a cooling fluid radially inward to a wheel space adjacent the shank thereof and radially inward of a trailing edge of the platform.
A typical turbomachine blade includes an airfoil that is coupled by a platform to a shank which mounts the turbomachine blade to either a casing or rotor of the turbomachine. A trailing edge of the airfoil couples to a trailing edge of the platform of the blade where the two parts are coupled by a fillet, e.g., a generally triangular shaped piece of material formed by welding or other metal combining methods. Historically, a trailing edge of the airfoil has been radially aligned with an aft portion of the platform, referred to as a cover plate. In certain new turbomachine models, however, airfoils having trailing edges that meet the trailing edge of the platform in a radially un-aligned configuration are provided. This arrangement decreases the stress in the fillet region.
New turbomachine models are also operating under higher temperatures than previous models, and thus are exposing blades thereof as having less material capability. The increased temperatures can lead to a variety of life limiting issues such as low cycle fatigue (LCF). Consequently, the fillet region represents an area of increasing concern for low cycle fatigue as higher operating temperatures are employed. Conventionally, turbomachine blades that require cooling include a plenum therein for delivering cooling fluid that feeds the cooling fluid to hot areas. For example, axially extending cooling openings in communication with the plenum are typically applied in the trailing edge of the blade's airfoil. Cooling openings have also been provided axially through the platform or the cover plate. Cooling fluid that flows through the cooling openings cools the shank and/or the trailing edge of the platform that extends downstream relative to the airfoil. The fillet and the area below the radially innermost cooling hole, just above the platform, however are not providing with cooling openings and are not directly cooled.